Electromagnetic Valve and Fixing Structure

ABSTRACT

An electromagnetic valve has: a coil; a casing encircling the coil and having a cylinder portion and nail portions; a movable core moving axially in the wound coil; a fixed core set at an opening end of the casing; a valve body fixed to the opening end of the casing together with the fixed core by bending inwards the nail portions; and a spool valve body moving axially in the valve body. The nail portion is provided with a wide width portion at a root side, a narrow width portion at a top side and a stepped portion between the wide width portion and the narrow width portion. The stepped portion is positioned at a substantially same position as an outer edge of one end portion of the valve body, or positioned at a cylinder portion side with respect to the one end portion outer edge of the valve body.

This application is a continuation of U.S. application Ser. No.14/955,614, filed on Dec. 1, 2015, which is a continuation of U.S.application Ser. No. 13/756,143, filed Jan. 31, 2013, now U.S. Pat. No.9,228,672, issued Jan. 5, 2016, which claims priority from JapanesePatent Application No. 2012-021486, filed on Feb. 3, 2012, thedisclosures if which are expressly incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to an electromagnetic valve and a fixingstructure used for, for instance, a variable valve timing controlapparatus of an internal combustion engine.

A related art electromagnetic valve has been disclosed in, for example,Japanese Patent Provisional Publication No. 2010-071359 (hereinafter isreferred to as “JP2010-071359”).

This electromagnetic valve is a valve that is provided at a cylinderhead of the internal combustion engine and used for supply/exhaustcontrol of working fluid (hydraulic oil) by switching an oil passage ofa hydraulic circuit leading to the variable valve timing controlapparatus. The electromagnetic valve is formed into a substantiallybottomed cylindrical shape, and has a valve body slidably housing,inside thereof, a spool valve body and an electromagnetic solenoid fixedto an axial direction one end portion of the valve body.

The electromagnetic solenoid mainly has a casing that is a cylindricalmagnetic material, a coil that is housed and positioned inside thecasing, two fixed cores that are provided at axial direction front andrear ends of the casing, a substantially cylindrical column-shapedmovable core that is slidably set in a cylindrical member provided at aninner circumference of the coil, and a non-magnetic material drivingshaft that is provided at a front end side of the movable core andpresses the spool valve body against a spring force of a return spring.

Front and rear ends of a body (a cylinder portion) of the casing areopen, and the casing is provided, at the front end side, with aplurality of nail portions formed integrally with the casing. Whenassembling each component, the fixed core at the front end side is fixedwith each nail portion bent inwards.

SUMMARY OF THE INVENTION

In a case of the related art electromagnetic valve in JP2010-071359,however, a width of each nail portion of the casing is substantiallysame from a root part up to a top end part of the nail portion, namelythat each nail portion is formed into a rectangular shape. A bendingpoint, upon crimping, of the nail portion thus becomes the root part, inother words, the nail portion is bent at the root part of the nailportion. Since this root part is positioned close to a height of thefixed core, this makes the bending harder.

That is, each nail portion has a relatively great width, therebyincreasing rigidity of the whole nail portion. Then, since the bendingpoint, upon crimping, of the nail portion is positioned close to theheight of the fixed core, a force upon crimping acts on an edge of thefixed core which is the bending point, and the force is dispersed orspread inwards in a direction perpendicular to the axis. As aconsequence, not only a squeezing or a gripping force of the crimping isnot adequately obtained, but also there is a risk that the edge of thefixed core will be greatly deformed.

It is therefore an object of the present invention to provide anelectromagnetic valve that is capable of suppressing the deformation ofa member, e.g. the fixed core, which is crimped with the nail portion,while adequately securing the squeezing force of the crimping.

According to one aspect of the present invention, an electromagneticvalve comprises: an annularly-wound coil; a casing that encircles anouter peripheral side of the coil and has (a) a cylinder portion, atleast one end side in an axial direction of which is open; and (b) aplurality of nail portions which are formed integrally with the openingend of the cylinder portion, a movable core that is housed movably inthe axial direction in an inner periphery of the coil; a fixed core thatis set at the opening end side of the casing; a hollow valve body thatis fixed to the opening end of the casing together with the fixed coreby bending inwards and deforming the nail portions; and a spool valvebody that moves in the axial direction in the valve body according tothe movement in the axial direction of the movable core. And the nailportion is provided with (c) a wide width portion formed at a root sideof the nail portion; (d) a narrow width portion formed at a top edgeside of the wide width portion; and (e) a stepped portion formed betweenthe wide width portion and the narrow width portion. And the steppedportion is positioned at a substantially same position as an outer edgeof one end portion of the valve body which abuts on the fixed core fromthe axial direction, or is positioned at a cylinder portion side withrespect to the one end portion outer edge of the valve body.

According to another aspect of the present invention, an electromagneticvalve comprises: an annularly-wound coil; a casing that encircles anouter peripheral side of the coil and has (a) a cylinder portion, oneend side in an axial direction of which is open; and (b) a plurality ofnail portions which are formed integrally with the opening end of thecylinder portion, a movable core that is housed movably in the axialdirection in an inner periphery of the coil; a fixed core that is set atat least the opening end of the casing; a hollow valve body that isfixed to the opening end of the casing together with the fixed core bybending inwards and deforming the nail portions; and a spool valve bodythat moves in the axial direction in the valve body according to themovement in the axial direction of the movable core. And the nailportion has a structure in which a predetermined portion of the nailportion, which is positioned between a root part side of the nailportion and an outer edge in the axial direction of the valve body, isbent inwards and deformed more easily than the root part of the nailportion.

According to a further aspect of the invention, a fixing structure thatfixes a second member to a first member, comprises: a plurality of nailportions formed at the first member, a top edge portion of the nailportion being deformed by crimping by which one end of the second memberis crimped together with the top edge portion of the nail portion, andthe nail portion is formed so that rigidity of a predetermined positionat the top edge portion side of the nail portion is lower than that of aroot part of the nail portion.

The other objects and features of this invention will become understoodfrom the following description with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged view of a main part of an electromagnetic valveaccording to a first embodiment of the present invention.

FIG. 2 is a schematic view of a variable valve timing control apparatusthat employs the electromagnetic valve of the present embodiment.

FIG. 3 is a perspective exploded view showing an electromagneticsolenoid that is provided in the electromagnetic valve.

FIG. 4 is a perspective view of the electromagnetic valve of the presentembodiment.

FIG. 5 is a side view of the electromagnetic valve of the presentembodiment.

FIG. 6 is a drawing viewed from an arrow A in FIG. 5.

FIG. 7A is a sectional view of the main part, showing a state beforeperforming crimping using a nail portion. FIG. 7B is a sectional view ofthe main part, showing a state after performing the crimping.

FIG. 8 is an enlarged view of the main part of the electromagnetic valveaccording to a second embodiment of the present invention.

FIG. 9 is an enlarged view of the main part of the electromagnetic valveaccording to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, the crimping is performed by bendinginwards and deforming each narrow width portion of a nail portion from aposition of a stepped portion that is formed between a wide widthportion and the narrow width portion of the nail portion with the nailportion being supported by and at the wide width portion that has highrigidity. A squeezing or a gripping force (a crimping force), in anaxial direction, to a fixed core is thus increased, and it is possibleto suppress the deformation of an edge of the fixed core.

Embodiments of an electromagnetic valve of the present invention willnow be explained below with reference to the drawings.

First Embodiment

In a first embodiment, the electromagnetic valve is applied to avane-type variable valve timing control apparatus of an internalcombustion engine.

The variable valve timing control apparatus will be briefly explainedwith reference to FIG. 2. The variable valve timing control apparatushas a timing sprocket 1 that is driven and rotates by an enginecrankshaft (not shown) through a timing chain, a camshaft 2 that iscapable of rotating relative to the timing sprocket 1, a relativeangular phase control mechanism (simply, a phase converter or aphase-change mechanism) 3 disposed between the timing sprocket 1 and thecamshaft 2 and changing or controlling a relative rotational positionbetween the timing sprocket 1 and the camshaft 2, and a hydrauliccircuit 4 that actuates the phase-change mechanism 3.

The camshaft 2 is rotatably supported by a cylinder head (not shown)through a camshaft bearing. The camshaft 2 has a plurality of drivingcams, each of which actuates an intake valve through a valve lifter.Each driving cam is formed integrally with the camshaft 2 at a certainposition on an outer peripheral surface of the camshaft 2.

The phase-change mechanism 3 has a cylindrical housing 5 provided at andfixedly connected to an inner circumference side of the timing sprocket1, a vane member 6 secured to one end portion of the camshaft 2 from anaxial direction by a cam bolt and relatively rotatably housed in thehousing 5, four shoes 7 formed integrally with an inner peripheralsurface of the housing 5, four vanes 8 formed integrally with the vanemember 6, and four retard oil chambers 9 and four advance oil chambers10. As can be seen in FIG. 2, the retard and advance oil chambers 9 and10 are divided and defined by the four shoes 7 and the four vanes 8.

The housing 5 has a front plate and a rear plate (both not shown) whichclose a front side opening end and a rear side opening end of thehousing 5 respectively. These housing 5 and front and rear plates aretightened together in the axial direction by four bolts 11, then fixedlyconnected together.

Each shoe 7 has a substantially trapezoidal shape in cross section.Further, a seal groove is formed on a top end part of the trapezoidalshape along the axial direction, and an almost square bracket(“]”)-shaped seal member 12 is fitted in the seal groove.

The vane member 6 is formed as an integral part by metal material. Thevane member 6 has a vane rotor 6 a and the four vanes 8. The vane rotor6 a is secured to the one end portion of the camshaft 2 from the axialdirection by the cam bolt with the cam bolt inserted into an insertionhole that is formed in the middle of the vane member 6. The four vanes 8are arranged at almost regular intervals in a circumferential directionof an outer peripheral surface of the vane rotor 6 a, and protrude in aradial direction.

The vane rotor 6 a is rotatably supported by the seal member 12 fittedin the seal groove on an upper surface of the top end part of each ofthe shoes 7 while making sliding contact with the seal member 12. Thevane rotor 6 a is provided with four retard side oil paths or holes (notshown) that communicate with the respective retard oil chambers 9 in theradial direction and four advance side oil paths or holes (not shown)that communicate with the respective advance oil chambers 10 in theradial direction.

Each of the vanes 8 is placed between the adjacent two shoes 7. A sealgroove is formed on a top end surface of each vane 8 along the axialdirection, and an almost square bracket (“]”)-shaped seal member 14 thatmakes sliding contact with the inner peripheral surface of the housing 5is fitted in the seal groove. Further, a locking mechanism 15 thatrestrains free rotation of the vane member 6 at a most-retarded angleside as shown in FIG. 2 is provided between the vane 8 having a maximumwidth and the rear plate.

The hydraulic circuit 4 has, as shown in FIG. 2, first and second oilpassages 16 and 17 that communicate with each retard oil chamber 9 andeach advance oil chamber 10 through each retard side oil passage andeach advance side oil passage respectively, an oil pump 19 that suppliesworking fluid (hydraulic oil) reserved in an oil pan 18 into each of theretard oil chambers 9 and the advance oil chambers 10 through the firstand second oil passages 16 and 17, and an electromagnetic valve 22 thatis provided at a downstream side of the oil pump 19 and selectivelyswitches oil passages with which the first and second oil passages 16and 17 communicate between a pump discharge oil passage 20 and an oildrain passage 21 by a control signal from an electronic controller 23.

As shown in FIGS. 2 to 6, this electromagnetic valve 22 is a directionswitching valve that switches ON/OFF of the oil passage. Theelectromagnetic valve 22 mainly has a cylindrical (a hollow) valve body36 inserted into and fixed to a valve accommodation hole that is formedat the cylinder head (not shown), an electromagnetic solenoid 37provided at one end side of the valve body 36, and a spool valve body 38housed movably (slidably) in the axial direction inside the valve body36 and moving by being pressed by an after-mentioned armature 45 that isa movable core moving to the electromagnetic solenoid 37 side by adriving force of the electromagnetic solenoid 37.

The valve body 36 has, inside thereof, a valve hollow 36 a for housingthe spool valve body 38, and an oil supply port 36 b at a substantiallymiddle position on an peripheral wall of the valve body 36. The oilsupply port 36 b is formed in the radial direction and opens to thevalve hollow 36 a. Further, first and second output ports 36 c and 36 dwhich individually communicate with the first and second oil passages 16and 17 respectively are provided at both side positions of the oilsupply port 36 b. These first and second output ports 36 c and 36 d areformed in the radial direction and open to the valve hollow 36 a.Furthermore, a drain port 36 e which communicates with the oil pan 18through the oil drain passage 21 is formed along the radial direction ata side position of the first output port 36 c. Here, each of the portsis provided, at an outer circumference thereof, with a ring-shapedfilter 24 a to 24 c for filtering dust and contaminant and the like.

To seal a gap between the valve accommodation hole and the valve body36, a seal ring 25 is fitted and fixed onto an outer circumference of abase end portion 39, at the electromagnetic solenoid 37 side, of thevalve body 36. Also, to seal a gap between an after-mentioned casing 40and the valve body 36 (the base end portion 39), a seal ring 26 isfitted and fixed to a top end side of the base end portion 39.

As shown in FIG. 1, the valve body 36 has a flange shaped ring portion39 a at an edge side, at the electromagnetic solenoid 37 side, of thebase end portion 39. The ring portion 39 a is formed integrally with thevalve body 36 (the base end portion 39), and makes contact with anafter-mentioned first fixed yoke 42 from the axial direction. Inaddition, the valve body 36 has a ring-shaped stopper groove 39 b at aside part of the ring portion 39 a. As will be explained later, a narrowwidth portion 47 b of a first nail portion 47 (both described later)stops at or grips this stopper groove 39 b by making contact with thisstopper groove 39 b by crimping. Here, as shown in FIG. 5 also FIG. 4, abreathing vent 36 f to ensure good sliding performance of the spoolvalve body 38 is formed at a bottom wall of the valve body 36.

The spool valve body 38 is formed as an integral part by metal material.As shown in FIG. 2, the spool valve body 38 is provided, on an outerperipheral surface of a valve shaft 38 a, with two cylindricalcolumn-shaped first and second land portions 38 b and 38 c. The firstand second land portions 38 b and 38 c are formed integrally with thespool valve body 38 (the valve shaft 38 a) at a certain interval, andselectively open/close the oil supply port 36 b, the first and secondoutput ports 36 c and 36 d and the drain port 36 e according to movingpositions of the first and second land portions 38 b and 38 c.

The electromagnetic solenoid 37 mainly has, as shown in FIG. 3, thesubstantially cylindrical casing 40 made of magnetic material, acylindrical electromagnetic coil (an annularly-wound coil) 41 set at aninner periphery of the casing 40, first and second fixed yokes 42 and 43which are two fixed cores fixed to front and rear opening ends of thecasing 40 by the crimping and demagnetized/magnetized by theelectromagnetic coil 41, the armature 45 housed movably (slidably) inthe axial direction inside a tubular yoke 44 that is arranged and fixedbetween both the fixed yokes 42 and 43, and a non-magnetic materialshaft 46 provided slidably in an axial hole of the first fixed yoke 42.

The casing 40 is formed into the cylindrical shape by rounding amagnetic material plate or sheet. As can be seen in FIG. 3, two roundengaging convex portions 40 b and two round engaging concave portions 40c corresponding to the round engaging convex portions 40 b, which areformed at opposing ends, in a circumferential direction, of thecylindrical shaped magnetic material plate, are engaged or fitted witheach other and joined together. A body (a cylinder portion) 40 a of thecasing 40 is then formed with front and rear ends of the cylinderportion 40 a open.

The front side opening end of the cylinder portion 40 a is provided withfour first nail portions 47 for fixing the first fixed yoke 42 by thecrimping, while the rear side opening end of the cylinder portion 40 ais provided with four second nail portions 48 for fixing the secondfixed yoke 43 by the crimping. The first and second nail portions 47 and48 are formed integrally with the respective opening ends of thecylinder portion 40 a, and protrude from the respective opening ends.

As shown in FIGS. 1, 3 to 6, the first and second nail portions 47 and48 are formed into a convex shape that protrudes from the front and rearedges of the cylinder portion 40 a respectively. Further, two first nailportions 47 are arranged, as a pair, at right and left positions whichare 180-degree positions in the circumferential direction of the frontside opening end. The remaining two first nail portions 47 are alsoarranged, as a pair, at right and left positions which are 180-degreepositions in the circumferential direction of the front side openingend. Likewise, two second nail portions 48 are arranged, as a pair, atright and left positions which are 180-degree positions in thecircumferential direction of the rear side opening end. The remainingtwo second nail portions 48 are also arranged, as a pair, at right andleft positions which are 180-degree positions in the circumferentialdirection of the rear side opening end.

As shown in the drawings, the first and second nail portions 47 and 48extend along the axial direction of the cylinder portion 40 a. Theprotruding first and second nail portions 47 and 48 have rectangularwide width portions 47 a and 48 a that are positioned at the cylinderportion 40 a side, narrow width portions 47 b and 48 b that are formedintegrally with the wide width portions 47 a and 48 a in thesubstantially middle at top edges of the wide width portions 47 a and 48a, and stepped portions 47 c and 48 c that are shoulder portions formedbetween the wide width portions 47 a, 48 a and the narrow width portions47 b, 48 b.

A width W1 of each of the narrow width portions 47 b and 48 b is set toapproximately one-third width of a width W of each of the wide widthportions 47 a and 48 a, then rigidity of the wide width portions 47 aand 48 a is higher than that of the narrow width portions 47 b and 48 b.That is, the wide width portions 47 a and 48 a having high rigidity andthe narrow width portions 47 b and 48 b having low rigidity are dividedor defined with the stepped portions 47 c and 48 c being the center orthe middle. Therefore, when performing the crimping, the first andsecond nail portions 47 and 48 are bent inwards with positions of thestepped portions 47 c and 48 c being respective bending points (bendinglines). On outer edges of top edge portions 47 d and 48 d of the narrowwidth portions 47 b and 48 b, tapered surfaces 47 e and 48 e are formed.

As shown in FIG. 1, each stepped portion 47 c at the valve body 36 sideis formed so as to be positioned at a substantially same position as anedge 39 c at the stopper groove 39 b side of the ring portion 39 a ofthe base end portion 39 of the valve body 36 when assembling the casing40 etc. On the other hand, each stepped portion 48 c at the rear edgeside is formed so as to be positioned at a substantially same positionas an outer edge of an after-mentioned cutting groove 43 c of the secondfixed yoke 43.

Here, a fixing bracket 49 for being secured to the cylinder head isfixed on an outer side surface of the cylinder portion 40 a of thecasing 40.

As shown in FIG. 3, the first fixed yoke 42 and the second fixed yoke 43has disk-shaped flange portions 42 a and 43 a and tubular portions 42 band 43 b. The tubular portions 42 b and 43 b are formed integrally withthe flange portions 42 a and 43 a at middle positions on inner surfaces,which are opposing surfaces in the axial direction, of the flangeportions 42 a and 43 a. Further, four arc cutting grooves 42 c and 43 care formed at substantially 180-degree positions in the circumferentialdirection of the flange portions 42 a and 43 a respectively.

The first fixed yoke 42 is provided, at a middle position of the flangeportion 42 a, with a shaft insertion hole 42 d that penetrates theflange portion 42 a and continues to an insertion hole of the tubularportion 42 b. An outside diameter of each of the flange portions 42 aand 43 a is set to the substantially same outside diameter as thecylinder portion 40 a of the casing 40. A width of each of the cuttinggrooves 42 c and 43 c is set to be slightly larger than a width of thewide width portions 47 a and 48 a of the first and second nail portions47 and 48 so that the wide width portions 47 a and 48 a can be fitted tothe cutting grooves 42 c and 43 c. Here, an outside diameter of the ringportion 39 a of the base end portion 39 of the valve body 36 is set tobe smaller than that of the flange portion 42 a by a thickness of eachfirst nail portion 47.

Further, a seal member 27 is inserted between an outer circumferentialportion of the flange portion 42 a of the first fixed yoke 42 and afront end flange 44 a of the tubular yoke 44.

The electromagnetic coil 41 is energized/deenergized (ON/OFF) by theelectronic controller 23 that is electrically connected to a terminal ina connector 41 a provided at an outer periphery of the electromagneticcoil 41.

The armature 45 has a substantially cylindrical column-shape, and is setso as to move forward by the fact that each of the yokes 42, 43 and 44is magnetized by the energization of the electromagnetic coil 41.

As shown in FIGS. 2 and 5, a compressed coil spring 50 is providedbetween the bottom wall of the valve body 36 and the spool valve body38. The compressed coil spring 50 forces the spool valve body 38 to aleft direction in FIG. 2, i.e. to an opposite direction to the movingdirection of the magnetized armature 45.

The shaft 46 is made of the non-magnetic material. A base end of theshaft 46 is in abutted-contact with a top end of the armature 45, whilea top end of the shaft 46 is in abutted-contact with one end of thespool valve body 38, then the shaft 46 moves in the axial direction by arelative pressure (a relative force) between the movement of thearmature 45 and the compressed coil spring 50.

In the following description, operation of the variable valve timingcontrol apparatus will be briefly explained. In a predetermined lowrotation speed region from an extremely low rotation speed during anengine operation at idle and upon an engine start, the energization ofthe electromagnetic valve 22 by the electronic controller 23 isinterrupted or shut off. Thus, the spool valve body 38 is held at a mostleftward position shown in FIG. 2 by a spring force of the compressedcoil spring 50. In this sate, the first land portion 38 b connects theoil supply port 36 b and the second output port 36 d, while the secondland portion 38 c shuts off a connection between the oil supply port 36b and the first output port 36 c and connects the first output port 36 cand the drain port 36 e.

The working fluid pumped out by the oil pump 19 is then supplied to eachretard oil chamber 9 through the first oil passage 16, while the workingfluid in each advance oil chamber 10 is returned to the oil pan 18 fromthe second oil passage 17 through the drain port 36 e and the oil drainpassage 21.

The vane member 6 is thus held at a most leftward rotation positionshown in FIG. 2, and the relative rotational position between the timingsprocket 1 and the camshaft 2 (a rotational phase of the camshaft 2relative to the timing sprocket 1) is set to the most-retarded angleside. With this operation, good engine startability can be ensured, alsostable engine rotation during the idle can be ensured.

When the engine operating condition shifts from the low rotation speedregion to a middle rotation speed region which is a steady operatingcondition, an ON signal is outputted to the electromagnetic valve 22from the electronic controller 23 and the electromagnetic valve 22 isenergized, the armature 45 is then magnetized. The armature 45consequently moves to a most rightward direction from the position shownin FIG. 2 against the spring force of the compressed coil spring 50, andmoves the spool valve body 38 to the same direction.

As a consequence, by the first land portion 38 b and the second landportion 38 c, the first output port 36 c communicates with the oilsupply port 36 b, and the connection with the drain port 36 e is shutoff. On the other hand, the connection between the second output port 36d and the oil supply port 36 b is shut off, and the second output port36 d communicates with the drain port 36 e.

The working fluid (hydraulic pressure) pumped out by the oil pump 19 isthen supplied to each advance oil chamber 10 through the second oilpassage 17 and an internal pressure of each advance oil chamber 10becomes high, while the working fluid (the hydraulic pressure) in eachretard oil chamber 9 is exhausted to the oil pan 18 and an internalpressure of each retard oil chamber 9 becomes low.

The vane member 6 thus rotates in a rightward direction from therotation position shown in FIG. 2, and the relative rotational positionbetween the timing sprocket 1 and the camshaft 2 (the rotational phaseof the camshaft 2 relative to the timing sprocket 1) is converted to anadvanced angle side. With this operation, open/close timing of theintake valve shifts to the advanced angle side, and good enginecombustibility during the steady operating condition can be ensured,thereby increasing fuel economy and an engine output.

Further, when the engine operating condition shifts to a high rotationspeed region, an OFF signal is outputted to the electromagnetic valve 22(the electromagnetic solenoid 37) from the electronic controller 23 andthe electromagnetic valve 22 is deenergized. The armature 45 then movesto the most leftward direction shown in FIG. 2 by the spring force ofthe compressed coil spring 50. As a consequence, in the same manner asthe above, the spool valve body 38 connects the oil supply port 36 b andthe second output port 36 d, and connects the first output port 36 c andthe drain port 36 e.

The working fluid (the hydraulic pressure) is then supplied to eachretard oil chamber 9 and its internal pressure becomes high, while theworking fluid (the hydraulic pressure) in each advance oil chamber 10 isexhausted to the oil pan 18 and its internal pressure becomes low.

The vane member 6 thus rotates in the most leftward direction shown inFIG. 2, and the camshaft 2 (the rotational phase of the camshaft 2relative to the timing sprocket 1) is set to a retarded angle side. Withthis operation, the open/close timing of the intake valve shifts to theretarded angle side, thereby increasing the engine output in a highrotation speed high load region.

In the present embodiment, when fixing the valve body 36 to the casing40 through the first fixed yoke 42 by the crimping, the electromagneticcoil 41, the tubular yoke 44, the armature 45, the shaft 46, etc. arepreviously housed in the casing 40, and subsequently the first fixedyoke 42 is set while fitting each of the wide width portions 47 a of thefirst nail portions 47 to the cutting groove 42 c.

Then, as shown in FIG. 7A, the base end portion 39 of the valve body 36is set between the first nail portions 47 while making an opposing endsurface of the base end portion 39 abut on a front end surface of theflange portion 42 a of the first fixed yoke 42 from the axial direction.At this time, each of the stepped portions 47 c of the first nailportions 47 faces to an edge of the ring portion 39 a, and each narrowwidth portion 47 b is positioned at an outer side of the stopper groove39 b.

Afterwards, as shown in FIG. 7B, by pressing the top edge portions 47 dof the narrow width portions 47 b of the first nail portions 47 from theaxial direction with a crimping punch 51, its pressing force acts oneach narrow width portion 47 b in an inward direction through eachtapered surface 47 e. Each narrow width portion 47 b having low rigidityis then bent inwards and deformed from or around the stepped portion 47c that is a base part or a root part. Therefore, each top edge portion47 d of the narrow width portion 47 b is fitted (or inserted) to thestopper groove 39 b and further is pressed against an inner surface ofthe stopper groove 39 b, that is, a whole inner surface of the narrowwidth portion 47 b is pressed against an outer surface of the ringportion 39 a (i.e. the inner surface of the stopper groove 39 b), andthus a squeezing force or a gripping force is exerted. By this crimpingforce (the squeezing force), the valve body 36 is firmly fixed to thecasing 40 from the axial direction.

As explained above, when the top edge portion 47 d of the narrow widthportion 47 b is pressed with the crimping punch 51, an inner surface ofeach wide width portion 47 a having high rigidity abuts on a bottomsurface of the cutting groove 42 c of the first fixed yoke 42 and theouter surface of the ring portion 39 a without deformation, then thewide width portion 47 a having high rigidity supports or facilitates theinward deformation (the inward bending) of the narrow width portion 47 bfrom the root part (i.e. from the stepped portion 47 c) withoutdeformation of the wide width portion 47 a itself.

With this fixation, a strong force dose not acts on the edge 39 c of thering portion 39 a around the stepped portion 47 c that is the bendingpoint (the bending line) of the narrow width portion 47 b, but thecrimping force is exerted on the outer surface of the ring portion 39 athrough the whole inner surface of the narrow width portion 47 b.Consequently, it is possible to suppress the deformation of an edge ofthe first fixed yoke 42 while adequately securing the squeezing force ofthe crimping.

Although the fixation of the crimping of the first nail portion 47 sidehas been explained above, the fixation of the crimping of the secondnail portion 48 side, in which the second fixed yoke 43 is crimped, isthe same as that of the first nail portion 47 side even though the valvebody 36 is not present at the second fixed yoke 43 side.

Here, in the present embodiment, although the width of the narrow widthportion 47 b is the same from the root part to the top end, it ispossible to change the width. For instance, a shape from the steppedportion 47 c to the narrow width portion 47 b could be an arc.

The stepped portion 47 c is a portion that does not continuously changethe rigidity of the first nail portion 47 from the wide width portion 47a to the narrow width portion 47 b, but brings a stepped change for therigidity of the first nail portion 47 so that only the narrow widthportion 47 b is bent and deformed with respect to the wide width portion47 a.

In the present embodiment, the casing 40 corresponds to a first member,and the valve body 36 corresponds to a second member.

Second Embodiment

FIG. 8 shows a second embodiment. In the second embodiment, two narrowwidth portions 47 b, 47 b are provided for each first nail portion 47.The narrow width portions 47 b, 47 b are formed at the top edge side ofthe wide width portion 47 a, i.e. at both sides in a width direction ofthe stepped portion 47 c, through an opening portion 47 e.

Thus, the present embodiment also has the same effect as that of thefirst embodiment, and further has an effect of increasing the crimpingforce by providing the two narrow width portions 47 b, 47 b for eachfirst nail portion 47.

Also in the second embodiment, the width of the narrow width portion 47b could be changed. For instance, the opening portion 47 e might beformed into an arc or a semicircle.

Third Embodiment

FIG. 9 shows a third embodiment. In the third embodiment, the narrowwidth portion 47 b is formed in the substantially middle, in a widthdirection, of the stepped portion 47 c that is the top edge of the widewidth portion 47 a, and further an enlarged width portion 47 g whosewidth is the same as that of the wide width portion 47 a is formedintegrally with a top edge of the narrow width portion 47 b.

In the third embodiment, as same as the above embodiments, although thebending point (the bending line) upon the crimping is positioned aroundthe root part of the narrow width portion 47 b, i.e. around the steppedportion 47 c, a pressing area of the bent enlarged width portion 47 gwhich presses the outer surface of the ring portion 39 a (i.e. the innersurface of the stopper groove 39 b) becomes large. Hence, a stable orfirm crimping force against the ring portion 39 a can be provided.

In the third embodiment, the narrow width portion 47 b is formed into asquare bracket (“]”)-shape between the wide width portion 47 a and theenlarged width portion 47 g by cutting, and the width of the narrowwidth portion 47 b is the same. However, the narrow width portion 47 bcould be formed into an arc or a semicircle by the cutting.

The electromagnetic valve of the present invention is not limited to theelectromagnetic valve having the structure or configuration of the aboveembodiments. Also the electromagnetic valve of the present invention isapplied to not only the variable valve timing control apparatus andvalve lift control apparatus of the internal combustion engine, but alsoused for an oil pressure control and an oil flow passage switchingcontrol of other equipment.

Further, besides the fixation of the electromagnetic valve, the presentinvention can be applied to a fixing structure in which two elements orcomponents are fixed by the crimping.

Furthermore, as the fixation of the electromagnetic valve, it is aproportional control type valve, an ON/OFF type valve, a multistage typevalve and the like.

From the foregoing, the present invention includes the followingstructure or configuration of the electromagnetic valve, and has thefollowing effects.

(a) In the above embodiment, the casing 40 is formed into a cylindricalshape by rounding a plate member and joining opposing ends incircumferential direction of the plate member together.

According to the above electromagnetic valve, a forming process of thecasing is easily performed.

(b) In the above embodiment, the casing (40) is made of magneticmaterial.

(c) In the above embodiment, two narrow width portions 47 b, 47 b areformed at the top edge both sides of the wide width portion 47 a with anopening portion 47 e provided between the two narrow width portions 47b, 47 b.

According to the above electromagnetic valve, by providing the twonarrow width portions 47 b, 47 b for each first nail portion 47, thecrimping force is increased.

(d) In the above embodiment, the narrow width portion 47 b is formed ina middle at the top edge side of the wide width portion 47 a, and anenlarged width portion 47 g whose width is the same as that of the widewidth portion 47 a is formed at a top edge of the narrow width portion47 b.

According to the above electromagnetic valve, since the pressing area ofthe bent enlarged width portion 47 g which presses the outer surface ofthe ring portion 39 a which is crimped together with first nail portion47 (i.e. the inner surface of the stopper groove 39 b) becomes large,the stable or firm crimping force against the ring portion 39 a can beprovided.

The entire contents of Japanese Patent Application No. 2012-21486 filedon Feb. 3, 2012 are incorporated herein by reference.

Although the invention has been described above by reference to certainembodiments of the invention, the invention is not limited to theembodiments described above. Modifications and variations of theembodiments described above will occur to those skilled in the art inlight of the above teachings. The scope of the invention is defined withreference to the following claims.

What is claimed is:
 1. An electromagnetic valve comprising: a pluralityof nail portions provided at one end in an axial direction of acylindrical casing, each of the nail portions including (a) a wide widthportion; and (b) a narrow width portion provided at a top end of thewide width portion; and a valve body fixed to the casing by the nailportions with the narrow width portion of each of the nail portionsbeing bent inwards, and an inclined surface being formed on an outeredge of a top edge portion of the narrow width portion.
 2. Theelectromagnetic valve as claimed in claim 1, wherein: a shoulder portionis formed at both sides of the narrow width portion.
 3. Theelectromagnetic valve as claimed in claim 1, wherein: a width of thenarrow width portion is set to substantially one-third width of a widthof the wide width portion.
 4. An electromagnetic valve comprising: anannularly-wound coil; a casing encircling an outer peripheral side ofthe coil and having a cylinder portion, at least one end side in anaxial direction of the cylinder portion being open; a plurality of nailportions, each of the nail portions including (a) a wide width portionformed integrally with an opening end of the cylinder portion; and (b) anarrow width portion formed integrally with the wide width portion in asubstantially middle in a width direction of the wide width portion at atop end side of the wide width portion; a movable core housed movably inthe axial direction in an inner periphery of the coil; a fixed coreincluding (c) a disk-shaped flange portion disposed at an opening endside of the casing; and (d) a plurality of cutting grooves formed at anouter circumferential side of the flange portion, the wide widthportions of the plurality of nail portions being fitted to the pluralityof cutting grooves, respectively; a hollow valve body having a ringportion that contacts the fixed core in the axial direction and fixed tothe opening end of the casing together with the fixed core with thenarrow width portion of the nail portion bent inwards; and a spool valvemoving in the axial direction in the valve body according to movement inthe axial direction of the movable core.
 5. A method for manufacturingan electromagnetic valve, the electromagnetic valve having anannularly-wound coil; a casing encircling an outer peripheral side ofthe coil and having a cylinder portion, at least one end side in anaxial direction of the cylinder portion being open; a plurality of nailportions, each of the nail portions including (a) a wide width portionformed integrally with an opening end of the cylinder portion; (b) anarrow width portion formed at a top end side of the wide width portion;and (c) an inclined surface formed on an outer edge of a top edgeportion of the narrow width portion; a movable core housed movably inthe axial direction in an inner periphery of the coil; a cylindricalvalve body provided through a fixed core that is disposed at an openingend side of the casing; and a spool valve moving in the axial directionin the valve body according to movement in the axial direction of themovable core, the method comprising: deforming the narrow width portioninwards by pressing, from the axial direction, the inclined surface ofthe nail portion that extends in the axial direction of the casing witha crimping punch; and fixing the valve body to the casing from the axialdirection.